Experimental and numerical study of LY315 steel moment connection with bolted cover plates

Abstract

To study the seismic performance of LY315 steel moment connection with bolted cover plates, the tests of three full-scale connection specimens subjected to cyclic loads were conducted. The slip resistance coefficient among high-strength bolts and LY315 steel plates was experimentally obtained. The failure modes, load-carrying capacities, hysteretic responses, deterioration performance, ductility, and energy dissipation capacities of the connections were investigated. The impact of the splicing position on the cyclic behavior of the connections was explored. Besides, the corresponding nonlinear numerical modeling approach was proposed, which was validated against the test results. Finally, the influence of the configuration details on seismic responses and damage control was discussed. The analysis results showed that the slip resistance coefficient with surface treatment of wire brush to remove floating rust was 0.29 for LY315 steel. The connections with bolted cover plates exhibited large load-carrying capacity, satisfactory energy dissipation capacity and ductility (the ultimate rotations of three specimens exceeded 0.04 rad, and the ductility coefficients were more than 5.0). When the cover plates were relatively stocky, as the decrease of the splicing position, the load-carrying capacities slightly decreased, while the deformed capacity and the cumulative dissipated energy of the specimens were slightly enhanced, which was probably caused by the local deformation of the cover plates and the slippage of bolts. The change of the splicing position had a minor effect on the stiffness degradation. The strategy of thickening the shear domain significantly enhanced the load-carrying capacities of the connections, and effectively lowered the shear deformation of these regions and the energy proportion of the column, however, the primary members of frame still dissipated most of the system energy. The strategies of shortening the splicing position or thinning the cover plates were effective options to mitigate the plasticity in the primary members and limit the damage within the replaceable cover plates.